Hmmm. What do your sim instructors have to say about it?
I would be wary of attempting to use a non-SOP technique from another aircraft. From what you describe, it sounds like you’re flaring maybe a little too much if you’re picking up significant drift in the de-crab? The wing produces a lot of ground effect, counterbalanced a bit by crossed controls and slip angles.
As for the rudder, I have yet to run out of authority. The 777 is a fair bit bigger in all dimensions than the 737 (which is what I came from, too) and if you attempt to align your heading with that of the runway at the same angular rate, you’ll be trying to move metal much more quickly. Maybe slow down the manoeuvre a tad?
No two sims are alike, in my experience. When I converted onto type, one sim rattled your teeth and the other one was always like butter, no matter what you did with the aircraft. When you get onto the real thing, I bet you don’t have any problems.